DESCRIPTION: While cigarette smoking has steadily declined for several years, the use of smokeless tobacco (ST) is increasing. Many ST users wish to quit but lack resources. There is a need for innovative, validated, and widely applicable low-cost interventions to facilitate ST cessation. An effective interactive Internet-based cessation program could meet this need. This proposed study will compare the efficacy of a tailored Internet-based interactive ST cessation program with a Web site that provides typical cessation materials and links to other Web-based ST resources. Smokeless tobacco users who wish to quit will be recruited to our Web site and randomized to receive either the personalized, interactive multimedia program plus links to other Web-based resources (Tailored Condition) or a cessation information site with links to other Web-based resources (Usual Care Condition). The Tailored Condition will be based on empirically validated ST cessation programs and will take advantage of the unique properties of the Internet to provide individualized cessation assistance, and social support via forums and chat rooms. After completion of entry criteria questions and informed consent, 2,400 ST users aged 18 and older will be equally randomized to either the Usual Care Condition or the Tailored intervention Condition. Cessation outcomes will be evaluated at 6 weeks, 6 months, and 12 months post-enrollment via Internet surveys. The primary outcomes are tobacco cessation at 6- and 12-month follow-up, with quit rates expected to be higher in subjects in the Tailored Condition. The study will also investigate baseline subject characteristics, program utilization, social support, and process variables as predictive of cessation outcomes. A cost analysis will determine the cost per quit and relative cost-effectiveness of the two conditions. The public health potential of the proposed Web-based application to promote smokeless tobacco cessation is great. The use of the Internet as a resource for health care information continues to grow. An empirical evaluation of this delivery system for smokeless tobacco cessation is warranted and timely.